Motor-truck.



F. M. PRETTYMAN.

"MOTOR TRUCK.

. APPLICATION FILE? APR. 22, 1913, 1 0 3 1 35 I Patented Dec. 30, 1913.

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F. M. PRE TYM-AN.

MOTOR TRUCK.

APPLICATION FILED APR. 22, 1913.

P11611181 Dec. 30, 1913. 1

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111 f. Fi e sin FRANCIS M. PBETTYMAN, OF MALLARD, MINNESOTA L MOTOR-TRUCK.

Specification of Letters Patent.

Patented Dec. 30,1913.

Application filed April 2%, 1913. Serial No. 762,818.

To all whom it may concern:

Be it known that I, FnANoI's M. PRETTY- MAN, 'a native-born citizen of the United and particularly effective four-wheel transmission gear for motor trucks, which, willv have the following advantages, namely, the

,power of the engine may be simultaneously transmitted to all of the wheels of the machine, including both the front steering wheels, and the ordinary rear. driving wheels; which will enable the machine to be operated without the employment of the usual brake, the mechanism serving to automatically lock the wheels when'the machine is brought to a standstill, thereby preventing the machine from moving forwardly or ,hackwardly, when being operated along a steep hill or incline, whether in a forward or backward direction, and which will greatly simplify and otherwise improve transmis: 'sion gear of the class described, consequently economizing in the cost'of manufacture and maintenance of the truck as a whole.

With the above and other objects in view, the invention consists in the construct-ion, combination and arrangement of parts, as will be hereinafter more fully described, illustrated in the accompanying drawings, and pointed out in the claims hereunto appended.

In the drawings: Figure 1 is a side elevation of a motor truck, embodying the pres:

'ent invention. Fig. 2 is a plan view of the same. Fig. 3 is a vertical cross section on the line3- 3 of Fig. 1. Fig. t is a vertic al longitudinal section on the line 44 of Fig. 2.

The truck contemplated in this invention is similar in its general construction and arrangement to that described in my .pendin application, Serial No. 748,7 O4, filed on or a out Februai-y 15th, 1913,.the truck com risinga frame composed of the main longitudinal side bars 1 spaced at any suitable distance apart and carrying the front and rear axles, as shown.

,The'" rear portion of the fraineof the machine has the side bars 2 thereof set at a greater distanceapart than the bars 1, all of said bars being, however, in parallel relation to each other, while the bars 2 are connected at their front and rear ends by the front and rear cross bars 3 and 4, respectively, said bars 3 and 4 being also fixedly related to and connected with the parallel main longitudinal bars 1.

The driving wheels 5 are mounted fast on the sections 6 of a centrally divided rear axle, as shown in Fig. 2, each section 6 of the driving axle being adapted to revolve independently of the other, after the manner of the ordinary differential car now in common use in automobiles. T e front axle is likewise divided centrally to comprise two sections 7 which are in line with each other, and which are geared to the steering wheels 8 for the purpose of driving the latter by means of the bevel ear wheels 9, 10 and 11. The knuckles o the steering wheels and the means for supporting the same together, with the means for turnin the steering wheels, bein fully describe in my copending application, it is unnecessary to go into a detailed description of the same herein, the only oint that it is necessary to understand being that the steering wheels 8are driven simultaneously with the rear or usual driving Wheels 5 of the ma chine.

Each of the driving axle sections 6 has fast thereon a worm gear wheel 12, and each of the front axle sections 7 also has a worm gear wheel 18 fast thereon, the teeth of the wheels 13 being pitched reversely to those. of the wheels 12, so that when the axle sections ter of the machine frame are arranged sub stantially parallel worm shafts 14, each ofwhich is provided at its opposite extremities with right and left hand worm gears 15 and 16 which mesh, respectively, with the wheels 12 and 13, above referred to.

17 designates a motor mounted at a suitfront of the same and parallel thereto, 'mo-' tion being transm tted from the engine shaft to the counter shaft by means of a sprocket.

' chain passing around sprocket wheels 21.

and 22 fa respectively, on the engine shaft and counter shaft. Arranged approximately under the counter shaft 19 is a friction wheel shaft 93 which has fast on its oppo site ends miter gan' wheels 24 which mesh with other miter gear wheels fast on the worm shafts let, hereinabove described, the motion of the shaft being thus transmitted to the worm shafts l4 and from the latter to the front and rear wheels 8 and 5. The shaft 23 is divided at or near its center int-o independently revolving sections, as shown in the plan view Fig. 2, and on the inner end of each of said sections is mounted fast a friction wheel 26, said wheels having wide faces and together forming a transversely elongated divided cylinder. .l'n advance of the wheels 26 is located a friction drive roller 27, the length of which is equal approximately to the combined length of the two wheels 26, a friction drive roller 28 of corresponding length but smaller diameter being located in rear of the wheels 26, as shown in the plan view. The, roller 27 is fast on a shaft 29 providedat one end with a sprocket wheel 30. The roller 28 is also mounted fast on a shaft 31 provided at the corresponding end with a sprocket wheel.

Fast on the counter shaft 19 is a sprocket I wheel 33, around which passes a sprocket chain 34, said chain passing around the sprocket wheel 82 on the shaft 31 and rearwardly around an idler sprocket wheel 35, and thence under and partly around the sprocket wheel 30. By means of the sprocket chain and wheels hereinabove just. described, the wheels 30 and 32 are driven in reverse directions, and, therefore, the friction drive rollers 27 and 28 are also driven in reverse directions simultaneously.

In order to shift the driving rollers 27 and .28 alternately into and out of engagement with the friction wheels .26, for the purpose of driving the latter forwardly or rearwardly, the shafts 29 and 3] are monnt ward direction at a speed commensurate with the character of said roller 27 in rela-' tion to the wheels 26, and when the roller 28 is shifted into frictional engagement with the wheels 26, the roller 27 being mnltaneously shifted out of engagement,-

l. direction of movement of the machine is reversed and the machine driven at a lower rate of speed, due to the relative decrease in diameter of the roller 28 as compared with the roller 27.

In turning the machine, the wheels at the outer side of the curve are enabled to travel faster than those at the inner side by reason of the fact that the shaft 23 is divided, and, therefore, a certain amount of slip may take place between one of the wheels 26 and the friction roller 27 or 28 in engagement therewith.

From the foregoing description, it will now be understood that the power is transmitted from the motor shaft to all four wheels of the machine, the steering wheels being driven as well as the rear driving wheels. .lt will also be understood that the sections of the front axle are d riven in a direction the reverse of that in which the rear axle sections are driven, whether the machine is moving in a forward or backward direction. Furthermore. friction gearing is he terposed between the motor.and the worm shafts, so that both of said shafts are simultaneonsly driven normally at the same speed, but. permitted to turn periodically at different relative speeds, in accordance with the radiusof the are described by the machine in making a turn. When the transmission frame is shifted to a central or neutral point, in which both of the friction drive rollers 27 and 528 are out of contact with the frietion wheels 26, the transmission gearing is locked, by reason of the fact that the worm gear wheels 12 and 13 cannot turn the worm gears 1-5 and 16, the result being that the sections of the front and" rear axles are all locked. This imparts the utmost safety to the machine in ascending or descending steep grades, for the reason that it is impossible for the machine to coast, either in a forward or backward direction. At the same time, itrnay be easily driven forwardly or backwardly by throwing one or the other of the friction drive rollers 27 and 28 into frictional drivingengagement with the wheels 26.

lVhilc I have hereinahore made reference to worm gears and worm wheels, it is to be understood thatspiral gears and wheels may he substitutedtherefor. the efficiency of both types of gears being equal in respect to the locking of the aide sections, when the transmission gear is thrown outof commission.

lVhatis claimed is: 1.. in four wheel transmission for motor tracks, a truck frame, front and rear axles each divided into two sections, steering wheels gearedto 'and driven by the front;

'aile sect-ions, driving wheels fast on the'rear driving axle sections, a worm gear wheel fast on each section" or the front and rear axles,

the gear wheels on the front axle operating in a. direction the reverse of those on the rear axle, substantially parallel worm shat'ts,

right and left hand worm gears on each shaft driving the worm wheels on the respective front and rear axle sections, and a motor 7 geared to both of said shafts.

2. In four wheel transmission for motor tracks, a truck frame, front and rear axles each divided into two sections, steering wheels geared to and driven by the front axle sections, driving wheels fast on the rear drivin axle sections, a worm gear wheel fast on eac section of the front and rear axles, the gear wheels on the front axle operating in a direction tilieareverse of those on the rear axle, substantially parallel worm shafts, right and left hand worm gears on each shaft driving the wornrwheels on the re spective front and rear axle sections, a mo tor, and friction driving mechanism interposed between the motor and said shafts.

3. In four wheel transmission for motor trucks, a truck frame, front and rear axles each divided into two sections, steering wheels geared to and driven by the front axle sections, driving wheels fast on the rear drivin axle sections, a worm gear Wheel fast on eac section of the front and rear axles, the gear wheels on the front axle operating in a direction the reverse of those on the rear axle, substantially parallel worm shafts, right and left hand worm gears on each shaft driving the worm Wheels on the respective front and rear axle sections, a motor, and friction driving and reversing mechanism interposed between the motor and said shafts.

In testimony whereof I atlix my signature in presence of two witnesses.

FRANCIS M. PRETTYMAN. Witnesses ERICK WALLIN, AUG. A. SCHNEIDER. 

